Stored blood platelets will be studied, measuring platelet shape, pH, pO2 and lactate formation under various conditions of storage and with various additives. The metabolism of GTP in red cells will be investigated, characterizing and separating GTPases in the membrane. studies of red cell preservation in GABPM, a bicarbonate containing buffered red cell storage medium will be carried out. Red cells from patients with hemolytic disease will be examined for metabolic defects.